scsi.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 1,249 行 · 第 1/3 页

/*
 *  scsi.c Copyright (C) 1992 Drew Eckhardt
 *         Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale
 *         Copyright (C) 2002, 2003 Christoph Hellwig
 *
 *  generic mid-level SCSI driver
 *      Initial versions: Drew Eckhardt
 *      Subsequent revisions: Eric Youngdale
 *
 *  <[e-mail]>
 *
 *  Bug correction thanks go to :
 *      Rik Faith <[e-mail]>
 *      Tommy Thorn <tthorn>
 *      Thomas Wuensche <[e-mail]>
 *
 *  Modified by Eric Youngdale [e-mail] or [e-mail] to
 *  add scatter-gather, multiple outstanding request, and other
 *  enhancements.
 *
 *  Native multichannel, wide scsi, /proc/scsi and hot plugging
 *  support added by Michael Neuffer <[e-mail]>
 *
 *  Added request_module("scsi_hostadapter") for kerneld:
 *  (Put an "alias scsi_hostadapter your_hostadapter" in /etc/modprobe.conf)
 *  Bjorn Ekwall  <[e-mail]>
 *  (changed to kmod)
 *
 *  Major improvements to the timeout, abort, and reset processing,
 *  as well as performance modifications for large queue depths by
 *  Leonard N. Zubkoff <[e-mail]>
 *
 *  Converted cli() code to spinlocks, Ingo Molnar
 *
 *  Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
 *
 *  out_of_space hacks, D. Gilbert (dpg) 990608
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/completion.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/unistd.h>
#include <linux/spinlock.h>
#include <linux/kmod.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/cpu.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi_request.h>

#include "scsi_priv.h"
#include "scsi_logging.h"


/*
 * Definitions and constants.
 */

#define MIN_RESET_DELAY (2*HZ)

/* Do not call reset on error if we just did a reset within 15 sec. */
#define MIN_RESET_PERIOD (15*HZ)

/*
 * Macro to determine the size of SCSI command. This macro takes vendor
 * unique commands into account. SCSI commands in groups 6 and 7 are
 * vendor unique and we will depend upon the command length being
 * supplied correctly in cmd_len.
 */
#define CDB_SIZE(cmd)	(((((cmd)->cmnd[0] >> 5) & 7) < 6) ? \
				COMMAND_SIZE((cmd)->cmnd[0]) : (cmd)->cmd_len)

/*
 * Data declarations.
 */
unsigned long scsi_pid;
static unsigned long serial_number;

/*
 * Note - the initial logging level can be set here to log events at boot time.
 * After the system is up, you may enable logging via the /proc interface.
 */
unsigned int scsi_logging_level;

const char *const scsi_device_types[MAX_SCSI_DEVICE_CODE] = {
	"Direct-Access    ",
	"Sequential-Access",
	"Printer          ",
	"Processor        ",
	"WORM             ",
	"CD-ROM           ",
	"Scanner          ",
	"Optical Device   ",
	"Medium Changer   ",
	"Communications   ",
	"Unknown          ",
	"Unknown          ",
	"RAID             ",
	"Enclosure        ",
};

/*
 * Function:    scsi_allocate_request
 *
 * Purpose:     Allocate a request descriptor.
 *
 * Arguments:   device		- device for which we want a request
 *		gfp_mask	- allocation flags passed to kmalloc
 *
 * Lock status: No locks assumed to be held.  This function is SMP-safe.
 *
 * Returns:     Pointer to request block.
 */
struct scsi_request *scsi_allocate_request(struct scsi_device *sdev,
					   int gfp_mask)
{
	const int offset = ALIGN(sizeof(struct scsi_request), 4);
	const int size = offset + sizeof(struct request);
	struct scsi_request *sreq;
  
	sreq = kmalloc(size, gfp_mask);
	if (likely(sreq != NULL)) {
		memset(sreq, 0, size);
		sreq->sr_request = (struct request *)(((char *)sreq) + offset);
		sreq->sr_device = sdev;
		sreq->sr_host = sdev->host;
		sreq->sr_magic = SCSI_REQ_MAGIC;
		sreq->sr_data_direction = DMA_BIDIRECTIONAL;
	}

	return sreq;
}

void __scsi_release_request(struct scsi_request *sreq)
{
	struct request *req = sreq->sr_request;

	/* unlikely because the tag was usually ended earlier by the
	 * mid-layer. However, for layering reasons ULD's don't end
	 * the tag of commands they generate. */
	if (unlikely(blk_rq_tagged(req))) {
		unsigned long flags;
		struct request_queue *q = req->q;

		spin_lock_irqsave(q->queue_lock, flags);
		blk_queue_end_tag(q, req);
		spin_unlock_irqrestore(q->queue_lock, flags);
	}


	if (likely(sreq->sr_command != NULL)) {
		struct scsi_cmnd *cmd = sreq->sr_command;

		sreq->sr_command = NULL;
		scsi_next_command(cmd);
	}
}

/*
 * Function:    scsi_release_request
 *
 * Purpose:     Release a request descriptor.
 *
 * Arguments:   sreq    - request to release
 *
 * Lock status: No locks assumed to be held.  This function is SMP-safe.
 */
void scsi_release_request(struct scsi_request *sreq)
{
	__scsi_release_request(sreq);
	kfree(sreq);
}

struct scsi_host_cmd_pool {
	kmem_cache_t	*slab;
	unsigned int	users;
	char		*name;
	unsigned int	slab_flags;
	unsigned int	gfp_mask;
};

static struct scsi_host_cmd_pool scsi_cmd_pool = {
	.name		= "scsi_cmd_cache",
	.slab_flags	= SLAB_HWCACHE_ALIGN,
};

static struct scsi_host_cmd_pool scsi_cmd_dma_pool = {
	.name		= "scsi_cmd_cache(DMA)",
	.slab_flags	= SLAB_HWCACHE_ALIGN|SLAB_CACHE_DMA,
	.gfp_mask	= __GFP_DMA,
};

static DECLARE_MUTEX(host_cmd_pool_mutex);

static struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost,
					    int gfp_mask)
{
	struct scsi_cmnd *cmd;

	cmd = kmem_cache_alloc(shost->cmd_pool->slab,
			gfp_mask | shost->cmd_pool->gfp_mask);

	if (unlikely(!cmd)) {
		unsigned long flags;

		spin_lock_irqsave(&shost->free_list_lock, flags);
		if (likely(!list_empty(&shost->free_list))) {
			cmd = list_entry(shost->free_list.next,
					 struct scsi_cmnd, list);
			list_del_init(&cmd->list);
		}
		spin_unlock_irqrestore(&shost->free_list_lock, flags);
	}

	return cmd;
}

/*
 * Function:	scsi_get_command()
 *
 * Purpose:	Allocate and setup a scsi command block
 *
 * Arguments:	dev	- parent scsi device
 *		gfp_mask- allocator flags
 *
 * Returns:	The allocated scsi command structure.
 */
struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, int gfp_mask)
{
	struct scsi_cmnd *cmd = __scsi_get_command(dev->host, gfp_mask);

	if (likely(cmd != NULL)) {
		unsigned long flags;

		memset(cmd, 0, sizeof(*cmd));
		cmd->device = dev;
		cmd->state = SCSI_STATE_UNUSED;
		cmd->owner = SCSI_OWNER_NOBODY;
		init_timer(&cmd->eh_timeout);
		INIT_LIST_HEAD(&cmd->list);
		spin_lock_irqsave(&dev->list_lock, flags);
		list_add_tail(&cmd->list, &dev->cmd_list);
		spin_unlock_irqrestore(&dev->list_lock, flags);
	}

	return cmd;
}				

/*
 * Function:	scsi_put_command()
 *
 * Purpose:	Free a scsi command block
 *
 * Arguments:	cmd	- command block to free
 *
 * Returns:	Nothing.
 *
 * Notes:	The command must not belong to any lists.
 */
void scsi_put_command(struct scsi_cmnd *cmd)
{
	struct Scsi_Host *shost = cmd->device->host;
	unsigned long flags;
	
	/* serious error if the command hasn't come from a device list */
	spin_lock_irqsave(&cmd->device->list_lock, flags);
	BUG_ON(list_empty(&cmd->list));
	list_del_init(&cmd->list);
	spin_unlock(&cmd->device->list_lock);
	/* changing locks here, don't need to restore the irq state */
	spin_lock(&shost->free_list_lock);
	if (unlikely(list_empty(&shost->free_list))) {
		list_add(&cmd->list, &shost->free_list);
		cmd = NULL;
	}
	spin_unlock_irqrestore(&shost->free_list_lock, flags);

	if (likely(cmd != NULL))
		kmem_cache_free(shost->cmd_pool->slab, cmd);
}

/*
 * Function:	scsi_setup_command_freelist()
 *
 * Purpose:	Setup the command freelist for a scsi host.
 *
 * Arguments:	shost	- host to allocate the freelist for.
 *
 * Returns:	Nothing.
 */
int scsi_setup_command_freelist(struct Scsi_Host *shost)
{
	struct scsi_host_cmd_pool *pool;
	struct scsi_cmnd *cmd;

	spin_lock_init(&shost->free_list_lock);
	INIT_LIST_HEAD(&shost->free_list);

	/*
	 * Select a command slab for this host and create it if not
	 * yet existant.
	 */
	down(&host_cmd_pool_mutex);
	pool = (shost->unchecked_isa_dma ? &scsi_cmd_dma_pool : &scsi_cmd_pool);
	if (!pool->users) {
		pool->slab = kmem_cache_create(pool->name,
				sizeof(struct scsi_cmnd), 0,
				pool->slab_flags, NULL, NULL);
		if (!pool->slab)
			goto fail;
	}

	pool->users++;
	shost->cmd_pool = pool;
	up(&host_cmd_pool_mutex);

	/*
	 * Get one backup command for this host.
	 */
	cmd = kmem_cache_alloc(shost->cmd_pool->slab,
			GFP_KERNEL | shost->cmd_pool->gfp_mask);
	if (!cmd)
		goto fail2;
	list_add(&cmd->list, &shost->free_list);		
	return 0;

 fail2:
	if (!--pool->users)
		kmem_cache_destroy(pool->slab);
	return -ENOMEM;
 fail:
	up(&host_cmd_pool_mutex);
	return -ENOMEM;

}

/*
 * Function:	scsi_destroy_command_freelist()
 *
 * Purpose:	Release the command freelist for a scsi host.
 *
 * Arguments:	shost	- host that's freelist is going to be destroyed
 */
void scsi_destroy_command_freelist(struct Scsi_Host *shost)
{
	while (!list_empty(&shost->free_list)) {
		struct scsi_cmnd *cmd;

		cmd = list_entry(shost->free_list.next, struct scsi_cmnd, list);
		list_del_init(&cmd->list);
		kmem_cache_free(shost->cmd_pool->slab, cmd);
	}

	down(&host_cmd_pool_mutex);
	if (!--shost->cmd_pool->users)
		kmem_cache_destroy(shost->cmd_pool->slab);
	up(&host_cmd_pool_mutex);
}

#ifdef CONFIG_SCSI_LOGGING
void scsi_log_send(struct scsi_cmnd *cmd)
{
	unsigned int level;
	struct scsi_device *sdev;

	/*
	 * If ML QUEUE log level is greater than or equal to:
	 *
	 * 1: nothing (match completion)
	 *
	 * 2: log opcode + command of all commands
	 *
	 * 3: same as 2 plus dump cmd address
	 *
	 * 4: same as 3 plus dump extra junk
	 */
	if (unlikely(scsi_logging_level)) {
		level = SCSI_LOG_LEVEL(SCSI_LOG_MLQUEUE_SHIFT,
				       SCSI_LOG_MLQUEUE_BITS);
		if (level > 1) {
			sdev = cmd->device;
			printk(KERN_INFO "scsi <%d:%d:%d:%d> send ",
			       sdev->host->host_no, sdev->channel, sdev->id,
			       sdev->lun);
			if (level > 2)
				printk("0x%p ", cmd);
			/*
			 * spaces to match disposition and cmd->result
			 * output in scsi_log_completion.
			 */
			printk("                 ");
			scsi_print_command(cmd);
			if (level > 3) {
				printk(KERN_INFO "buffer = 0x%p, bufflen = %d,"
				       " done = 0x%p, queuecommand 0x%p\n",
					cmd->buffer, cmd->bufflen,
					cmd->done,
					sdev->host->hostt->queuecommand);

			}